This invention relates to a high voltage power supply for laboratory applications and, more particularly, to a dual output power supply for monitoring and controlling two electrophoresis experiments at the same time.
Electrophoresis is a separation method involving the movement of charged molecules in an electrical field. The electrophoresis process occurs in a laboratory appliance such as a supporting medium or gel. The gel reduces the distorting effects of diffusion and helps to further separate the moving molecules. Most electrophoresis apparatus provide two buffer chambers. The gel is positioned so that each end is in one of the buffer chambers with the gel being the only connection between them. The leads from the buffer chambers are connected to a power supply, and an electrical field is created when the power is applied. In the electrical field, one buffer is the cathode and the other buffer is the anode. Thus, any sample applied on the gel will move according to its charge. U.S. Pat. No. 4,612,106 relates to the field of electrophoresis and is hereby incorporated by reference.
A known single output power supply, such as catalog number 433-3300 manufactured by Buchler Instruments Division, Labconco Corporation, Kansas City, Mo., can monitor and control a single electrophoresis experiment. However, to monitor and control two electrophoresis experiments at the same time, a second single output power supply must be utilized.
The known single output power supply, referenced above, utilizes a microprocessor to control the application. Specifically, the microprocessor stores selected parameter values and monitors the actual parameter values as the application is executed. Accordingly, the actual parameter values are adjusted if they exceed the selected values.
For many applications, a single parameter such as voltage is selected to control the entire experiment. Then, by selecting the desired voltage and the maximum values for the other parameters, the application will operate at constant voltage. However, if the maximum capacity of the power supply is exceeded for current or power, the application will operate at a reduced voltage.
The known single output power supply also allows for crossover between parameters. That is, if voltage is the controlling parameter and the selected maximum value for either milliamps or watts is exceeded by the actual value, then the power supply will automatically cross over to constant current or constant power as the controlling parameter. This crossover feature is especially useful during an electrophoresis experiment because the gel's resistance typically decreases over the course of the experiment. Thus, when voltage is controlling, the current and wattage values rise because they are proportional to resistance.
The primary disadvantage of the known single output power supply is inefficiency. Prior to the present invention, each additional application required an additional single output power supply. Otherwise, the applications must be conducted one after the other. Typically, a single electrophoresis experiment will last from one to eighteen hours. Consequently, running two or more independent applications with a single output power supply requires either the added space and expense of providing additional power supplies, or the inconvenience of running the applications consecutively, which consumes considerably more time than running the applications concurrently.